Recursive Function and increment global/persistant variable

My code goes like below.

function [out1] = MyFun1(Arg1,Arg2,Arg3)
global z
If z~=n (n is a number passed in Arg3 )
function [out2]=MyFun2(Arg1,Arg2,Arg3)
out1=out2;
z=z+1;
MyFun1(Arg1,Arg2,Arg3)
end
out1=out2;
end

I want to take the output of 1st iteration and perform same operation on 1st result and again take that result and perfrom same operation. Repeat the process for z times.

I tried both recursive and persistant but I am not sure what mistake am I doing. Myfun1 and Myfun2 are replica only if i can handle recusrsive withing a single function I can modify my code.

[darova]

Use button for code inserting

[Rik]

Try to describe the goal of your code step by step. Your short description sounds like you would either need a loop, or a normal recursion. I see no indication that you would need a global.

[darova]

Can't use for loop? Only recursive?

[Amishi]

I want to call a function n times and each iteration i need the 1st output as input.

For Eg if I have a matrix X and for operations I have some matrix A,B,C and so on

1st Iteration

X1= X+A;

2nd iteration

X2=X1+B;

3rd itertaion

X3=X2+C;

I am passing A,B,C as an cell of matrix and final i want to return X3

I rewrote my code as below

% Main function
%%% code for arg1, arg2,arg3;
global P
global Q
P=4;
Q=1;
out =fun1(arg1,arg2,arg3,P,Q);

Function file

fun [out1]=input1(arg1,arg2,arg3,P,Q)
if (Q~=P)
    XX=fun2(arg1,arg2,arg3);
    input1(arg1,arg2,XX,P,Q+1);
end
out1=XX;
end

so in this case if Q=4 it exits the loop so my intializing issue has been solved

But when i debug the code out1 rolls backs to Q=4,3,2 and the result in out in the main program is not X3 instead X1

I am not sure on how to rectify it. Please help.

Answer 1

[Rik]

You could do this with a recursive function, but it is a better idea to use a for-loop:

%generate some random data
sz=[5 30];
ABCD=cell(1,4);
for n=1:numel(ABCD),ABCD{n}=rand(sz);end

%now the calculation:
X=ABCD{1};
for n=2:numel(ABCD)
    X=X+ABCD{n};
end

Or even better, you could use the sum function, although this only works if this is exactly what you want to do (the for-loop allows function calls if you need them).

tmp=cat(ndims(ABCD{1})+1,ABCD{:});
X=sum(tmp,ndims(tmp));